It has been the practice to provide ceramic coats on various cookware such as pots, pans, and the like, and particularly aluminum based cookware. Normally, ceramic and ceramic clad surfaces have poor release properties because of their inherently high surface energies. Food residues, and especially those formed after cooking, tend to adhere with some tenacity to ceramic and ceramic clad surfaces. At the same time, organic coatings commonly used on cookware suffer from poor abrasion resistance and hardness, expecially when hot. Cookware is often subject to wear due principally to abrasion against other parts while in use, such as cooking utensils.
Various approaches have been taken in the past to improve both the release properties and abrasion resistance of cookware and the like. One approach included applying a discontinuous coating on a substrate that amounted to a series of glassy, spaced-apart minute lumps on the substrate around and over which a release coating was deposited. In terms of volume, the release coating predominated over the glassy lumps. While the lumps afforded some abrasion protection to the release coating as from scraping by a cooking utensil, the protection was incomplete and the release coating tended to be substantially unprotected and had a relatively short useful life.
The present invention improves cookware and other suitable substrates in need of such protection by forming a composite layer over the substrate that has effectively both improved abrasion-resistant and release properties as well as an improved adherence to the substrate by physically interlocking with it.